1. Field of the Invention
The present disclosure is generally related to a communication module including an off-channel signal detector with a programmable hysteresis comparator.
2. Description of the Related Art
Radio frequency receivers that are used in wireless devices, such as cellular telephones, typically receive a variety of signals and noise in addition to receiving and detecting the desired signal carrying communication information. The desired signal is often referred to as the channel and the other signals are referred to as off-channel signals. Strong off-channel signals produce spurious products within the channel due to non-linearity in the receiver, often impairing normal reception. With the presence of strong off-channel signals, an off-channel signal detector within the receiver may trigger a flag to indicate a strong off-channel signal condition so that adjustments may be made within the receiver to adapt to the strong off-channel condition, and preserve overall receiver linearity. One method of detecting the off-channel signal condition is to compare a detected energy level of off-channel signals against a threshold. When the detected energy level exceeds the threshold, the off-channel signal condition is indicated. A problem with this off-channel signal detection method is that due to integrated circuit process mismatches, a significant ripple in the output of the threshold detection element often causes an unstable condition (chattering) of a resulting off-channel condition detection circuit and can lead to a breakdown in operation of the receiver.
Accordingly, there is a need for an improved off-channel signal detector for use in communication receivers.
The use of the same reference symbols in different drawings indicates similar or identical items.